The vast majority of infants can sit on the lumbar bench around 5-7 months, but there are certain differences depending on the development. According to the normal growth and development pattern of infants, two lift three turn six will sit, seven roll eight crawl week will walk. That is, under the normal growth and development pattern of infants, generally 6 months can sit alone. If the infant is well developed, it can be advanced to 5 months, and if the development is late, it can be delayed to 7 months. But usually, because the infant growth and development is not yet perfect, bones, muscle strength is not complete, too early to sit on the waist stool, may cause adverse effects on growth and development. Therefore, parents are advised to try to let their babies sit on the lumbar stool at around 6 months of age according to the development of the baby, but it is not recommended to sit for a long time. Usually after the infant reaches 8 months, the time of sitting on the lumbar stool can be extended appropriately. Different infant growth and development, will sit time is different, even if 1-2 months later, are normal, parents do not need to worry too much.